Transmission configuration and method for controlling a transmission

ABSTRACT

A transmission configuration includes an automated dual-clutch transmission having two transmission sections with respective input shafts, respective output shafts and respective motor clutches. The motor clutches are connected, on a motor side thereof, to a drive shaft and to a respective one of the input shafts on a transmission side thereof. A drive-side speed sensor unit is disposed at the drive shaft. An input-side speed sensor configuration includes sensor wheels connected, fixed against relative rotation, to respective ones of the input shafts, and pulse sensors disposed stationary with respect to a housing and within an effective range of the respective sensor wheels. The input-side speed sensor configuration is configured to detect a speed of the input shafts and a direction of rotation of at least one of the input shafts. A method for controlling an automated dual-clutch transmission is also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation, under 35 U.S.C. § 120, of copendingInternational Application No. PCT/EP2005/010031, filed Sep. 16, 2005,which designated the United States; this application also claims thepriority, under 35 U.S.C. § 119, of German Patent Application No. DE 102004 046 558.4, filed Sep. 24, 2004; the prior applications are herewithincorporated by reference in their entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to a transmission configuration and a method forcontrolling a transmission. More specifically, the invention relates toa sensor configuration for an automated dual-clutch transmission withtwo transmission sections, each having a motor clutch connected on amotor side thereof, via a drive shaft, to a drive motor, an input shaftconnected to the motor clutch on a transmission side thereof, and gearwheel sets forming a group of gear stages and each including a fixedgear and an idler gear, wherein a connection with a gear ratio betweenthe input shaft and an output shaft can be established with the gearstages by in each case engaging a gear clutch assigned to the idlergear, wherein the output shaft forms a power take-off shaft connected toan axle drive or wherein the output shaft is permanently connected tosuch a power take-off shaft, and with a sensor configuration with atleast a drive-side speed sensor unit disposed at the drive shaft, afirst input-side speed sensor unit disposed at the input shaft of afirst one of the transmission sections, and a second input-side speedsensor unit disposed at the input shaft of the second one of thetransmission sections, wherein the input-side speed sensor units includea respective sensor wheel connected, fixed against relative rotation, toa respective one of the input shafts and a respective pulse sensordisposed stationary with respect to a housing and within an effectiverange of the respective sensor wheel. The invention furthermore relatesto a method for controlling such an automated dual-clutch transmission.

The dual-clutch transmission has been known for quite a while as atransmission concept and is for example disclosed in German PatentApplication Publication No. DE 35 46 454 A1, however, in practice it hasbeen available in the form of an automated dual-clutch transmission onlyrecently in some production passenger vehicles. The dual-clutchtransmission includes a first transmission section with a first inputshaft, wherein a first motor clutch and in most cases several gearwheelsets, which each form a gear stage, are assigned to the first inputshaft and includes a second transmission section with a second inputshaft, wherein a second motor clutch and several gearwheel sets, whichform further gear stages, are assigned to the second input shaft. On theoutput side, the dual-clutch transmission can have a common outputshaft, which is connected to the gearwheel sets of both transmissionssections or can be connected to them and, in this case, forms a powertake-off shaft connected to the axle drive of a driven vehicle axle. Inorder to achieve an installation length that is as short as possible,which is in particular important in case of a transverse mounting of thedrive unit, which is formed of the drive motor and the dual-clutchtransmission, it is however also possible for the transmission sectionsof the dual-clutch transmission to have respective separate outputshafts, which are disposed in a V-shape about the input shafts, whichare usually disposed coaxial with respect to one another, wherein theoutput shafts are connected, via a power take-off gearing, with a commonpower take-off shaft. In case of such a dual-clutch transmission, theshift process between two gear stages, i.e. between an engaged load gearstage and a target gear stage to be engaged, which are assigned todifferent transmission sections, includes first engaging the target thegear stage, which usually is accomplished with a gear clutch, which isassigned to an idler gear of the corresponding gear stage and can beactuated via a shift collar, and subsequently, in a time-overlappingmanner, separating the motor clutch assigned to the input shaft of theload the gear stage and closing the motor clutch assigned to the inputshaft of the target gear stage. As a result, the power transmission isaccomplished in a respective alternating manner via the first and thesecond input shaft and is not interrupted during the shift process,which is why the dual-clutch transmission falls in the category of powershift transmissions. In order to perform as many shift processes aspossible in the described manner, the gear stages are assigned in analternating manner to the two transmission sections, i.e. onetransmission section includes the odd forward gear stages and the othertransmission section includes the even forward gear stages.

Since the actuation of the two motor clutches, in particular thetime-overlapping actuation, in such a shift process is extremely complexand cannot be accomplished with an acceptable mechanical outlay in amanual-mechanical manner, the conventional dual-clutch transmissions areembodied as automated transmissions and have several controllableactuators for actuating the motor clutches and the gear clutches as wellas several speed sensor units for ascertaining required speedinformation and information related to a direction of rotation. As isfor example disclosed in German Patent Number Nos. DE 199 39 818 C1 andDE 199 39 819 C1, conventional dual-clutch transmissions have at leastone drive-side speed sensor unit disposed at the drive shaft, a firstinput-side speed sensor unit disposed at the first input shaft of thefirst transmission section and a second input-side speed sensor unitdisposed at the second input shaft of the second transmission section,and a speed sensor unit on the power take-off side, which is in mostcases embodied speed sensitive and sensitive to a direction of rotationand is disposed at a power take-off shaft, which is connected to an axledrive or at an output shaft which is permanently connected to the powertake-off shaft. The drive-side speed sensor unit and the two input-sidespeed sensor units provide the speed on the motor side and,respectively, on the transmission side of the two motor clutches and aretherefore mainly used for controlling the two motor clutches. The speedsensor unit on the power take-off side provides the speed and thedirection of rotation of the power take-off shaft connected to the axledrive and is in particular used during driving-off processes forascertaining the state of motion of the concerned motor vehicle, i.e.detecting a forward movement, a stopping of the vehicle, a backwardsmovement and the value of the movement speed. The speed sensor unit onthe power take-off side is furthermore also used for diagnostic purposessuch as a checking a plausibility of the effective gear ratio andmonitoring the speed of the drive shaft.

A disadvantage of this sensor configuration is however the large numberof speed sensor units that is used and in particular the spatialdistance between the speed sensor unit on the power take-off side andthe other speed sensor units. The high number of speed sensor unitsresults in relatively high costs for purchasing, mounting and wiring aswell as corresponding fault possibilities during operation. Due to thespatial distance of the speed sensor unit on the power take-off side, itis practically impossible to combine all speed sensor units in a modulethat can be pre-assembled so that they can be installed together. Theplacement of the speed sensor unit on the power take-off side at thepower take-off shaft or an output shaft connected to the power take-offshaft is unfavorable with respect to the signaling system because theseshafts have a relatively small speed which results in a reduced temporalresolution of the associated sensor signals and thus results in adelayed detection of a movement of the motor vehicle. As is disclosed inGerman Patent Application Publication No. DE 103 08 218 A1, thisdeficiency can be remedied by an additional evaluation of the sensorsignal of a simple drive-side speed sensor unit disposed at a fasterrotating gear shaft. However, this requires an increased outlay withrespect to system and process engineering.

SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide a transmissionconfiguration and a method for controlling a transmission which overcomethe above-mentioned disadvantages of the heretofore-known methods andconfigurations of this general type. It is in particular an object ofthe invention to provide a transmission configuration whose sensorconfiguration is cost-effective and saves space and allows performingtypical control functions of a dual-clutch transmission withoutlimitations or restrictions. Another object of the invention is toprovide a method for controlling a transmission which allows performingtypical control functions of a dual-clutch transmission with a reducednumber of speed sensor units.

With the foregoing and other objects in view there is provided, inaccordance with the invention, a transmission configuration, including:

a drive shaft configured to be connected to a motor;

an automated dual-clutch transmission including a housing and twotransmission sections with respective input shafts, respective outputshafts and respective motor clutches, the motor clutches having a motorside and a transmission side, and the motor clutches being connected tothe drive shaft on the motor side of the motor clutches and beingconnected to a respective one of the input shafts on the transmissionside of the motor clutches;

an axle drive;

each of the transmission sections including gearwheel sets, thegearwheel sets forming a respective group of gear stages and havingrespective fixed gears and respective idler gears;

each of the transmission sections including gear clutches assigned tothe idler gears such that, when a given one of the gear clutchesassigned to a given one of the idler gears is engaged, a respective oneof the input shafts is connected to a respective one of the outputshafts with a given gear ratio, and the respective one of the outputshafts is operatively connected to the axle drive;

a drive-side speed sensor unit disposed at the drive shaft; and

an input-side speed sensor configuration including a first sensor wheelconnected, fixed against relative rotation, to a first one of the inputshafts, a second sensor wheel connected, fixed against relativerotation, to a second one of the input shafts, a first pulse sensordisposed stationary with respect to the housing and within an effectiverange of the first sensor wheel, and a second pulse sensor disposedstationary with respect to the housing and within an effective range ofthe second sensor wheel, the input-side speed sensor configuration beingconfigured to detect a speed of the input shafts and a direction ofrotation of at least one of the input shafts, the drive-side speedsensor unit and the input-side speed sensor configuration forming asensor configuration for controlling the automated dual-clutchtransmission.

In accordance with another feature of the invention, the first sensorwheel and the first pulse sensor form a first input-side speed sensorunit, the first input-side speed sensor unit is sensitive to speed andsensitive to a direction of rotation, the second sensor wheel and thesecond pulse sensor form a second input-side speed sensor unit.

In accordance with another feature of the invention there is provided, apower take-off shaft connected to the axle drive, the respective one ofthe output shafts is operatively connected to the axle drive by beingpermanently connected to the power take-off shaft.

In accordance with a further feature of the invention, the respectiveone of the output shafts which is operatively connected to the axledrive forms a power take-off shaft connected to the axle drive.

In accordance with yet another feature of the invention, the firstsensor wheel is a rotary-direction encoded sensor wheel and the firstpulse sensor is a simple pulse sensor.

In accordance with another feature of the invention, the drive-sidespeed sensor unit disposed at the drive shaft includes a pulse sensor;and the first pulse sensor, the second pulse sensor, and the pulsesensor of the drive-side speed sensor unit are combined in apre-assembled module in order to be installed together.

In other words, according to the invention, there is provided a sensorconfiguration for controlling an automated dual-clutch transmission withtwo transmission sections, each having a motor clutch connected on amotor side thereof, via a drive shaft, to a drive motor, an input shaftconnected to the motor clutch on a transmission side thereof, and gearwheel sets forming a group of gear stages and each including a fixedgear and an idler gear, wherein a connection with a gear ratio betweenthe input shaft and an output shaft can be established with the gearstages by in each case engaging a gear clutch assigned to the idlergear, wherein the output shaft forms a power take-off shaft connected toan axle drive or wherein the output shaft is permanently connected tosuch a power take-off shaft, with at least a drive-side speed sensorunit disposed at the drive shaft, a first input-side speed sensor unitdisposed at the first input shaft of the first transmission section, anda second input-side speed sensor unit disposed at the second input shaftof the second transmission section, each input-side speed sensor unitincluding a sensor wheel connected, fixed against relative rotation, toa respective input shaft and a pulse sensor disposed stationary withrespect to a housing and within an effective range of the sensor wheel,characterized in that a speed sensor unit, which is speed sensitive andsensitive to a direction of rotation, is disposed at least at an inputshaft of one of the two transmission sections.

As will be explained in more detail below, it is possible to accomplishtypical control functions of the dual-clutch transmission for which sofar the speed sensor unit on the power take-off side was needed, byusing the input-side speed sensor unit according to the invention, whichis speed sensitive and sensitive to a direction of rotation, and it ispossible to accomplish the control functions with an even bettertemporal resolution due to the increased rotational speed of the inputshaft. This allows either to eliminate the speed sensor unit on thepower take-off side or to increase the operational reliability of thetransmission control by performing the appropriate control functions incase of a defect of one of the two speed sensor units, which are speedsensitive and sensitive to a direction of rotation, in each case by therespective other speed sensor unit.

The new speed sensor unit, which is speed sensitive and sensitive to adirection of rotation, is preferably realized by a correspondingembodiment of one of the input-side speed sensor units that are alreadypresent in order to avoid a further, separate speed sensor unit. Inother words, one of the two input-side speed sensor units is configuredto be speed sensitive and sensitive to a direction of rotation.

The speed sensor unit that is sensitive to speed and to a direction ofrotation, is preferably formed by a sensor wheel that is encoded withrespect to a direction of rotation (rotary encoder wheel) and a simplepulse sensor, whose general concept is in principle known, because thistype of construction is especially cost-effective and space saving andrequires only one signal line.

In particular when saving the speed sensor unit on the power take-offside, it is possible to advantageously combine the pulse sensors of thedrive side speed sensor unit and the two input-side speed sensor unitsand, if applicable, also an additional input-side speed sensor unit,which is sensitive to speed and sensitive to a direction of rotation, ina pre-assembled module that can be installed together.

With the objects of the invention in view there is also provided, amethod for controlling a transmission, which includes the steps ofproviding an automated dual-clutch transmission with two transmissionsections, each having a motor clutch connected on a motor side thereof,via a drive shaft, to a drive motor, an input shaft connected to themotor clutch on a transmission side thereof, and gear wheel sets forminga group of gear stages and each including a fixed gear and an idlergear, wherein a connection with a gear ratio between the input shaft andan output shaft can be established with the gear stages by in each caseengaging a gear clutch assigned to the idler gear, wherein the outputshaft forms a power take-off shaft connected to an axle drive or whereinthe output shaft is permanently connected to such a power take-offshaft, and with a sensor configuration with at least a drive-side speedsensor unit disposed at the drive shaft, a first input-side speed sensorunit disposed at the input shaft of a first one of the transmissionsections, and a second input-side speed sensor unit disposed at theinput shaft of the second one of the transmission sections; anddetermining a speed and a direction of rotation of the power take-offshaft by using an input-side speed sensor unit which is speed sensitiveand sensitive to a direction of rotation, by first, with an opened motorclutch, engaging a gear stage of a transmission section including theinput-side speed sensor unit, by ascertaining, with the input-side speedsensor unit, a speed and a direction of rotation of the input shaft of arespective transmission section, and by subsequently calculating a speedand a direction of rotation of the power take-off shaft from the speedand the direction of rotation of the input shaft with a gear ratio and,if applicable, a reversal of a direction of rotation of an engaged gearstage.

This allows to reliably ascertain the speed and the direction ofrotation of the power take-off shaft while avoiding a signal evaluationof the speed sensor unit on the power take-off side, wherein expedientlythe smallest gear stage of the respective transmission section isengaged in order to achieve a greatest possible temporal resolution ofthe rotational motion of the power take-off shaft. The method accordingto the invention, which is mainly used in a driving-off process in orderto determine a vehicle movement, such as a forward movement of thevehicle, a stopping of the vehicle, a backward movement of the vehicleand a movement speed, can thus be used for saving, i.e. eliminating, thespeed sensor unit on the power take-off side or, if desired, forincreasing the operational reliability as a backup method in case of adefect of the speed sensor unit on the power take-off side.

In case of assigning the speed sensor unit that is speed sensitive andsensitive to a direction of rotation to the transmission section thatincludes the driving-off gear stage, it is expedient to engage thedriving-off gear stage in a driving-off process for ascertaining thevehicle movement.

However, if the driving-off occurs with a driving-off gear stage of theother transmission section, then, in order to ascertain the vehiclemovement, a gear stage is engaged as an auxiliary gear stage in thetransmission section that includes the speed sensor unit that is speedsensitive and sensitive to a direction of rotation, in order toestablish a connection to the power take-off shaft.

After finishing the driving-off process, the auxiliary gear stage isagain disengaged if in a directly subsequent shift process a differentgear stage is provided as a target gear stage. The auxiliary gear stagecan however advantageously remain engaged if it is provided as a targetgear stage in a directly subsequent shift process.

With the objects of the invention in view there is also provided amethod for controlling a transmission, which includes the steps ofproviding an automated dual-clutch transmission with two transmissionsections, each having a motor clutch connected on a motor side thereof,via a drive shaft, to a drive motor, an input shaft connected to themotor clutch on a transmission side thereof, and gear wheel sets forminga group of gear stages and each including a fixed gear and an idlergear, wherein a connection with a gear ratio between the input shaft andan output shaft can be established with the gear stages by in each caseengaging a gear clutch assigned to the idler gear, wherein the outputshaft forms a power take-off shaft connected to an axle drive or whereinthe output shaft is permanently connected to such a power take-offshaft, and with a sensor configuration with at least a drive-side speedsensor unit disposed at the drive shaft, and an input-side speed sensorunit disposed at the input shaft of one of the two transmissionsections; and determining a speed of the input shaft of one transmissionsection by using an input-side speed sensor unit of another transmissionsection, by first, with a respective engaged gear stage in bothtransmission sections, ascertaining, with the input-side speed sensorunit, a speed of the input shaft of the other transmission section andby subsequently calculating the speed of the input shaft of the onetransmission section from the ascertained speed with the gear ratios ofboth engaged gear stages.

In a similar manner it is also possible to determine a direction ofrotation of the input shaft of the one transmission section with theinput-side speed sensor unit of the other transmission section, that isconfigured to be sensitive to a direction of rotation, by first, with arespective engaged gear stage in both transmission sections,ascertaining, with this input-side speed sensor unit, a direction ofrotation of the input shaft of the other transmission section and bysubsequently calculating the direction of rotation of the input shaft ofthe one transmission section from the direction of rotation with thechanges in a direction of rotation of the gearwheel sets of both engagedgear stages. In this case, however, in contrast to the above-describeddetermination of the speed of the input shaft of the one transmissionsection, it is necessary to configure the applicable input-side speedsensor unit such that it is sensitive to the direction of rotation.

With the described procedure it is possible to determine the speed andthe direction of rotation of the input shaft of that transmissionsection whose input-side speed sensor is not used, while avoiding asignal evaluation of the speed sensor unit on the power take-off side aswell as one of the two input-side speed sensor units. The methodaccording to the invention, which is mainly used for a sequential shiftprocess, i.e. in the present case a shift process between a load gearstage of the other transmission section and a target gear stage of theone transmission section, can thus alternatively be used as a backupmethod in case of a defect in one of the two input-side speed sensorunits for increasing the operational reliability and for eliminating oneof the two input-side speed sensor units.

Since in a sequential shift process the motor clutch of the transmissionsection that includes the target gear stage is closed by using acontrol, whereas the motor clutch of the transmission section includingthe load gear stage is in most cases opened without using a control, itis desirable to know the speed of the input shaft of the transmissionssection that includes the target gear stage until the end of the shiftprocess, i.e. until a complete closing of the concerning motor clutchoccurs. Therefore, in case of a shift process, in which only the sensorsignal of the input-side speed sensor unit of the transmission sectionthat includes the load gear stage is used, the load gear stage remainsexpediently engaged until the motor clutch assigned to the target gearstage is completely closed. In other words, a mode of the inventionincludes, in case of a shift process between a load gear stage assignedto the other transmission section and a target gear stage assigned tothe one transmission section, leaving the load gear stage engaged untila motor clutch assigned to the target gear stage is completely closedfor determining a speed and/or a direction of rotation of the inputshaft of the one transmission section by using the input-side speedsensor unit of the other transmission section.

The method according to the invention can however also be used, in adriving-off process with the driving-off gear stage of the onetransmission section, for determining the speed of the assigned inputshaft with the input-side speed sensor unit of the other transmissionsection, if a gear stage is engaged as an auxiliary gear stage in theother transmission section. In other words, a mode of the inventionincludes, in case of a driving-off process with a driving-off gear stageof the one transmission section, engaging a gear stage in the othertransmission section as an auxiliary gear stage for determining a speedand/or a direction of rotation of the respective input shaft by usingthe input-side speed sensor unit of the other transmission section.

In this case, a gear stage, which is the next higher gear stage withrespect to the driving-off gear stage of the one transmission section,is engaged as an auxiliary gear stage, because this gear stage is with ahigh probability the target gear stage of a shift process directlysubsequent to the driving-off process.

With the objects of the invention in view there is also provided amethod for controlling a transmission, which includes the steps ofproviding an automated dual-clutch transmission with two transmissionsections, each having a motor clutch connected on a motor side thereof,via a drive shaft, to a drive motor, an input shaft connected to themotor clutch on a transmission side thereof, and gear wheel sets forminga group of gear stages and each including a fixed gear and an idlergear, wherein a connection with a gear ratio between the input shaft andan output shaft can be established with the gear stages by in each caseengaging a gear clutch assigned to the idler gear, wherein the outputshaft forms a power take-off shaft connected to an axle drive or whereinthe output shaft is permanently connected to such a power take-offshaft, and with a sensor configuration with at least a drive-side speedsensor unit disposed at the drive shaft, a first input-side speed sensorunit disposed at the input shaft of a first one of the transmissionsections, and a second input-side speed sensor unit disposed at theinput shaft of the second one of the transmission sections; anddetermining, in case of an external synchronization of the gear stagesin a shift process between a load gear stage assigned to the first oneof the transmission sections and a target gear stage assigned to thesecond one of the transmission sections, an output-side speed of thegear clutch of the target gear stage with the first input-side speedsensor unit of the first one of the transmission sections, by firstascertaining, with the first input-side speed sensor unit, a speed ofthe input shaft of the first one of the transmission sections and bysubsequently calculating from the ascertained speed with an effectivetransmission ratio between the respective input shaft and the gearclutch of the target gear stage, an output-side speed of the gear clutchof the target gear stage.

For an external synchronization of the gear stages, which is for exampleaccomplished via auxiliary drives which are connected to the inputshafts of the transmission sections, it is necessary to know the speedson both sides of the respective gear clutch, i.e. the input-side speedand the output-side speed. The input-side speed of the gear clutch is inthis case usually determined through the use of the input-side speedsensor unit of the same transmission section, wherein, in case the gearclutch is arranged on the output shaft, a conversion with the gear ratioof the concerned gear stage is performed. The output-side speed of thegear clutch can however be determined in accordance with the inventionthrough the use of the input-side speed sensor unit of the othertransmission section, while avoiding a signal evaluation of the speedsensor unit on the power take-off side, in that the determined speed ofthe input shaft of this sensor unit is calculated back with theeffective transmission ratio between this input shaft and the gearclutch of the target gear stage, wherein this gear ratio, in case theconcerned gear clutch is disposed on the output shaft, corresponds tothe gear ratio of the load gear stage and, in case it is disposed on theinput shaft, corresponds to the quotient of the gear ratios of the loadgear stage and the target gear stage.

Other features which are considered as characteristic for the inventionare set forth in the appended claims.

Although the invention is illustrated and described herein as embodiedin a dual-clutch transmission configuration and a method for controllinga dual-clutch transmission, it is nevertheless not intended to belimited to the details shown, since various modifications and structuralchanges may be made therein without departing from the spirit of theinvention and within the scope and range of equivalents of the claims.

The construction and method of operation of the invention, however,together with additional objects and advantages thereof will be bestunderstood from the following description of specific embodiments whenread in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a drive train with a dual-clutchtransmission and a sensor configuration according to the invention; and

FIG. 2 is a schematic view of a drive train with a dual-clutchtransmission and a sensor configuration according to the prior art.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the figures of the drawings in detail and first,particularly, to FIG. 2 thereof, there is shown a conventional drivetrain 1 of a motor vehicle wherein a dual-clutch transmission 2 isconnected on its input side, via a drive shaft 3 and a vibration damper4, to a drive motor 5 which is embodied as an internal combustionengine. On its power take-off side, the dual-clutch transmission 2 isconnected, via a power take-off shaft 6, to an axle drive 7, whichtransfers a torque, which is generated by the drive motor 5 and which isconverted in the dual-clutch transmission, via drive shafts 8 to drivenwheels 9.

The dual-clutch transmission 2 is formed of two transmission sections10, 11, a first transmission section 10 and a second transmissionsection 11, which are disposed partly coaxial with respect to oneanother, however in FIG. 2 they are shown in a schematic exploded viewin order to provide a better overview.

The first transmission section 10 includes a first motor clutch 12,which is connected, on its motor side, to the drive shaft 3 and isconnected, on its transmission side, to a first input shaft 13. Thefirst input shaft 13 is selectively connectable to a first output shaft18 via one of the several gearwheel sets 14, 15, 16, 17, each of whichconstitutes a respective gear stage. The gearwheel sets 14, 15, 16, 17respectively include a fixed gear 14 a, 15 a, 16 a, 17 a, which isrespectively connected, in a manner fixed against relative rotation, tothe first input shaft 13 or to the first output shaft 18, and an idlergear 14 b, 15 b, 16 b, 17 b, which is rotatably mounted on the firstoutput shaft 18 or the first input shaft 13. The gearwheel sets 14, 15,16, 17 of the first transmission section respectively form a gear stage,in this case a first forward gear stage G1, a third forward gear stageG3, a fifth forward gear stage G5 and a seventh forward gear stage G7.The gear stages G1, G3, G5, G7 can be selectively engaged and disengagedvia two shift collars 19, 20, each of which being assigned to respectivetwo gear stages, and gear clutches 14 c, 15 c, 16 c, 17 c, which areassigned to respective idler gears 14 b, 15 b, 16 b, 17 b. The firstoutput shaft 18 is permanently in connection with a power take-off shaft6 via a power take-off gearing 21 a.

The second transmission section 11 includes a second motor clutch 22,which is connected, on its motor side, to the drive shaft 3 and isconnected, on its transmission side, to a second input shaft 23. Thesecond input shaft 23 is selectively connectable to a second outputshaft 28 via one of the several gearwheel sets 24, 25, 26, 27, each ofwhich constitutes a respective gear stage. The gearwheel sets 24, 25,26, 27 respectively include a fixed gear 24 a, 25 a, 26 a, 27 a, whichis respectively connected, in a manner fixed against relative rotation,to the second input shaft 23 or to the second output shaft 28, and anidler gear 24 b, 25 b, 26 b, 27 b, which is rotatably mounted on thesecond output shaft 28 or the second input shaft 23. The gearwheel sets24, 25, 26, 27 of the second transmission section form in this case asecond forward gear stage G2, a fourth forward gear stage G4, a sixthforward gear stage G6 and a reverse gear stage R, which achieves areversal of the direction of rotation of the second output shaft 28 withrespect to the forward gear stages G2, G4, G6 by using an intermediategear 27 d which is provided between the fixed gear 27 a and the idlergear 27 b. The power and smash 27 b. The gear stages G2, G4, G6, R canbe selectively engaged and disengaged via two shift collars 29, 30, eachof which being assigned to respective two gear stages, and gear clutches24 c, 25 c, 26 c, 27 c, which are assigned to respective idler gears 24b, 25 b, 26 b, 27 b. The second output shaft 28 is also permanently inconnection with a power take-off shaft 6 via a power take-off gearing 21b.

The power transmission from the drive motor 5 to the axle drive 7 isaccomplished alternately via the first transmission section 10 and thesecond transmission section 11. A sequential shift process between aload gear stage, for example the third forward gear stage G3, of onetransmission section 10 and a target gear stage, for example the fourthforward gear stage G4, of the other transmission section 11 isaccomplished, with gear stages G3, G4 being engaged at the same time, ina time-overlapping control of the two motor clutches 12, 22, duringwhich the motor clutch 12 of the load gear stage G3 is opened and themotor clutch 22 of the target gear stage G4 is closed without aninterruption of the tractive force.

For the control of the two motor clutches 12, 22, in particular duringdriving-off processes and shift processes, the dual-clutch transmission2 normally includes a sensor configuration 31 with a speed sensor unit32 on the drive side, that is disposed at the drive shaft 3, a firstspeed sensor unit 33 on the input side, that is disposed at the firstinput shaft 13, and a second speed sensor unit 34 on the input side,that is disposed at a second input shaft 23. The conventional sensorconfiguration 31 includes in this case also a speed sensor unit 35 onthe power take-off side, that is disposed at the second output shaft 28in particular for detecting a vehicle movement during driving-offprocesses, such as when the vehicle moves forward, stops, movesbackwards, and for detecting a movement speed, and for a plausibilitycheck of the respective active gear stage. The speed sensor units 32,33, 34, 35, of which the speed sensor unit 35 on the power take-off sideis configured to be sensitive to speed and sensitive to the direction ofrotation, which is symbolized in the illustration of the speed sensorunit 35 in FIG. 2 by a dividing line, and the remaining speed sensorunits 32, 33, 34 are configured to be only speed sensitive, areconnected, via sensor lines 36, 37, 38, 39, to an evaluation unit 40,which is connected to a transmission control device (not shown) or whichis a component of the transmission control device. Actuators (not shown)for actuating the motor clutches 12, 22 and the shift collars 19, 20,29, 30 are controlled by the transmission control device.

In the drive train 1 shown in FIG. 1, in an otherwise identicalconfiguration, one of the two speed sensor units 33, 34 on the inputside, is configured to be sensitive to (rotational) speed and to thedirection of rotation in accordance with the invention, in the presentcase the first speed sensor unit 33′ on the input side is configured tobe sensitive to the speed and to the direction of rotation which issymbolized in the illustration of the speed sensor unit 33′ in FIG. 1 bya dividing line. The speed sensor units 33′, 34 preferably includesensor wheels (encoder wheels) 53, 54 and pulse sensors 43, 44. As isexplained in an exemplary manner in the following, this provides thepossibility, to perform typical control functions of the dual-clutchtransmission 2 without an evaluation of the sensor signals of the speedsensor unit 35 on the power take-off side and, if applicable, evenwithout an evaluation of the sensor signals of the second speed sensorunit 34 on the input side which is only sensitive to speed. This canoptionally be used for saving, i.e. eliminating, the respective speedsensor units 34, 35 or for maintaining the ability to operate thedual-clutch transmission 2 in case of a defect of these speed sensorunits 34, 35 and consequently for increasing operational reliability ofthe dual-clutch transmission 2. A possible elimination or a defect ofthe respective speed sensor units 34, 35 is indicated in FIG. 1 byrepresenting the speed sensor units 34, 35 and the associated sensorlines 38, 39 in dashed lines.

In accordance with the invention, the speed and the direction ofrotation of the power take-off shaft 6 can be determined through the useof the first speed sensor unit 33′ on the input side, in that, with thefirst motor clutch 12 opened, at first, a gear stage G1, G3, G5, G7 ofthe first transmission section 10 is engaged, in that the speed and thedirection of rotation of the first input shaft 13 is determined throughthe use of the speed sensor unit 33′, and in that subsequently the speedand the direction of rotation of the power take-off shaft 6 iscalculated from the speed and the direction of rotation of the inputshaft 13 with the gear ratio and (if applicable) a reversal of thedirection of rotation of the engaged gear stage G1, G3, G5, G7 byassigning a reverse gear stage to the first transmission section 10,which is theoretically possible but not present in this case. In thiscase, in order to achieve a greatest possible temporal resolution of arotational motion of the power take-off shaft 6, whose fast and exactdetection is important for determining a vehicle movement in particularin case of a driving-off process, the smallest (lowest) gear stage G1 isexpediently engaged, in other words in the present case the first gearstage G1 is engaged.

Engaging the first gear stage G1 for determining the speed and thedirection of rotation of the power take-off shaft 6 with the first speedsensor unit 33′ on the input side is optimal with respect to thetemporal resolution, no matter whether one drives off with the firstgear stage G1 of the first transmission section 10 or the second gearstage G2 of the second transmission section 11. In the last mentionedcase it may however also be expedient to engage the third gear stage G3for determining the speed and the direction of rotation of the powertake-off shaft 6, because this gear stage G3 has a high probability ofbeing the target gear stage in the directly following shift process andthus it can initially remain engaged after the driving-off process.

Furthermore, the speed of the second input shaft 23 can also bedetermined with the sensor configuration 31′ according to the inventionthrough the use of the first speed sensor unit 33′ on the input side,namely by first determining the speed of the first input shaft 13 bymeans of the speed sensor unit 33′ in case of a respective engaged gearstage (G3, G4) in both transmissions sections 10, 11, and bysubsequently calculating the speed of the second input shaft 23 fromthis speed with the gear ratios of the two engaged gear stages (G3, G4).This method can be used for a shift process between a load gear stage ofone transmission section and a target gear stage of the othertransmission section and can also be used for a driving-off process witha driving-off gear stage of the second transmission section 11. In caseof shifting into a target gear stage (G4) of the second transmissionsection 11 it is expedient for an exact determination of the speed ofthe second input shaft 23 to leave the load gear stage (G3) of the firsttransmission section 10 in its engaged state until the second motorclutch 22 is completely closed. In a driving-off process with adriving-off gear stage, e.g. the second gear stage G2, of the secondtransmission section 11, a gear stage of the first transmission section10 is engaged as an auxiliary gear stage for determining the speed ofthe second input shaft 23 by means of the first speed sensor unit 33′ onthe input side, wherein expediently the gear stage which is the nexthigher one to the driving-off gear stage G2 of the second transmissionsection 11 is engaged, i.e. in the present case the third gear stage G3of the first transmission section 10.

Finally, in case of an external synchronization of the gear stages in ashift process between a load gear stage G1, G3, G5, G7, which isassigned to the first transmission section 10, and a target gear stageG2, G4, G6, R, which is assigned to the second transmission section 11,the method according to the invention can also be used to determine thespeed of the gear clutch 24 c, 25 c, 26 c, 27 c on the output-side bymeans of the first speed sensor unit 33′ on the input side. This is doneby first determining the speed of the first input shaft 13 with thespeed sensor unit 33′, and by subsequently calculating from this speedthe speed on the output-side of the gear clutches 24 c, 25 c, 26 c, 27 cof the target gear stage G2, G4, G6, R with the effective gear ratiobetween the respective input shaft 13 and the gear clutch 24 c, 25 c, 26c, 27 c of the target gear stage G2, G4, G6, R.

LIST OF REFERENCE NUMERALS

1 drive train

2 dual-clutch transmission

3 drive shaft

4 vibration damper

5 drive motor

6 power take-off shaft

7 axle drive

8 drive shaft

9 wheel

10 (first) transmission section

11 (second) transmission section

12 (first) motor clutch

13 (first) input shaft

14, 15, 16, 17 gearwheel set

14 a, 15 a, 16 a, 17 a fixed gear

14 b, 15 b, 16 b, 17 b idler gear

14 c, 15 c, 16 c, 17 c gear clutch

18 (first) output shaft

19, 20 shift collar

21 a, 21 b power take-off gearing

22 (second) motor clutch

23 (second) input shaft

24, 25, 26, 27 gearwheel set

24 a, 25 a, 26 a, 27 a fixed gear

24 b, 25 b, 26 b, 27 b idler gear

24 c, 25 c, 26 c, 27 c gear clutch

27 d intermediate gear

28 (second) output shaft

29, 30 shift collar

31, 31′ sensor configuration

32 drive-side speed sensor unit

33, 33′ (first) input-side speed sensor unit

34 (second) input-side speed sensor unit

35 speed sensor unit on the power take-off side

36, 37, 38, 39 sensor line

40 evaluation unit

43, 44 pulse sensor

53, 54 sensor wheel

G1-G7 (forward) gear stage

R (reverse) gear stage

1. A method for controlling a transmission, the method which comprises:providing an automated dual-clutch transmission with two transmissionsections, each having a motor clutch connected on a motor side thereof,via a drive shaft, to a drive motor, an input shaft connected to themotor clutch on a transmission side thereof, and gear wheel sets forminga group of gear stages and each including a fixed gear and an idlergear, wherein a connection with a gear ratio between the input shaft andan output shaft can be established with the gear stages by in each caseengaging a gear clutch assigned to the idler gear, wherein the outputshaft forms a power take-off shaft connected to an axle drive or whereinthe output shaft is permanently connected to such a power take-offshaft, and with a sensor configuration with at least a drive-side speedsensor unit disposed at the drive shaft, a first input-side speed sensorunit disposed at the input shaft of a first one of the transmissionsections, and a second input-side speed sensor unit disposed at theinput shaft of the second one of the transmission sections; anddetermining a speed and a direction of rotation of the power take-offshaft by using an input-side speed sensor unit which is speed sensitiveand sensitive to a direction of rotation, by first, with an opened motorclutch, engaging a gear stage of a transmission section including theinput-side speed sensor unit, by ascertaining, with the input-side speedsensor unit, a speed and a direction of rotation of the input shaft of arespective transmission section, and by subsequently calculating a speedand a direction of rotation of the power take-off shaft from the speedand the direction of rotation of the input shaft with a gear ratio and,if applicable, a reversal of a direction of rotation of an engaged gearstage.
 2. The method according to claim 1, which comprises engaging asmallest one of the gear stages of the respective transmission sectionin order to achieve a maximum temporal resolution of a rotational motionof the power take-off shaft.
 3. The method according to claim 1, whichcomprises using an ascertainment of the speed and the direction ofrotation of the power take-off shaft in a driving-off process in orderto determine a vehicle movement.
 4. The method according to claim 3,which comprises determining a vehicle movement selected from the groupconsisting of a forward movement of a vehicle, a stopping of a vehicle,a backwards movement of a vehicle, and a movement speed of a vehicle. 5.The method according to claim 3, which comprises engaging a driving-offgear stage for determining the vehicle movement, in case the input-sidespeed sensor unit, which is speed sensitive and sensitive to a directionof rotation, is assigned to a transmission section including thedriving-off gear stage.
 6. The method according to claim 3, whichcomprises, in case the input-side speed sensor unit, which is speedsensitive and sensitive to a direction of rotation is assigned to atransmission section which does not include a driving-off gear stage,engaging a gear stage as an auxiliary gear stage in the transmissionsection which does not include the driving-off gear stage in order todetermine the vehicle movement.
 7. The method according to claim 6,which comprises selectively disengaging the gear stage used as theauxiliary gear stage after finishing the driving-off process if, in adirectly subsequent shift process, another gear stage is provided as atarget gear stage and leaving the gear stage used as the auxiliary gearstage engaged if, in a directly subsequent shift process, the gear stageis provided as a target gear stage.